The present invention relates generally to a flexible printed circuit (FPC) that connects one unit of a device to another unit of the device and, more specifically, to an FPC that inhibits the migration of water along the FPC.
Some electronic devices, such as portable computers and flip-type cell phones, are manufactured as two units, which are mechanically connected to each other with a hinge. In order for power and signals to be exchanged between the two units, an FPC may be used to electrically couple the two units. FIG. 1 is a top perspective view of one end of an FPC 100 connected to, for example, a keyboard case 10. As illustrated in FIG. 2A, the FPC 100 may include conductive traces 102 embedded between a pair of resin strips 104 and is bonded to a base plate 106 of the keyboard case 10. To reduce the possibility of water or other liquid from a spill migrating into the unit 10 to which the FPC 100 is connected, the tail exit of the FPC 100 may be covered with a water-tight film 108, such as Mylar®. However, as illustrated in the cross-sectional view of FIG. 2B, there may be gaps 110 at the edge of the water-tight film 108 that can create channels along the edges of the strips 104, increasing the possibility of intrusion of liquid into the gaps 110 and into the unit 10. The resin strips 104, and therefore the gaps 110, may be about 0.25 millimeters (mm) thick.
Therefore, it can be seen that there is a need for a more effective method of reducing liquid migration from the tail exit of an FPC into connected devices.